WASTE PRODUCTS FROM MEAT

Dominion, Volume 34, Issue 157, 29 March 1941, Page 7

WASTE PRODUCTS FROM MEAT

Days Of The Digester

lu view of the restrictions on the killing of various types of animals in the Dominion’s meat works, Some of the remarks made by Mr. A. C. Mitchell, M.l.Mech.E., in his chairman’s address to the Wellington branch of the New Zealand Institute of Engineers this week are of particu lar interest.

The recovery of waste products from offal and carcases goes back, so far as New Zealand is concerned, to the 1880’s, said Mr. Mitchell. In those days, every reputable meat works was equipped with a digester. This can be likened to a huge pot, into which was thrown all manner of unsavoury meats and offal, to say nothing of bones, and the whole thing was boiled, sometimes as much as tons at a time. Steam was used and the process lasted about four hours. At the end of the boil, cold water was introduced, which had the result of floating the fats out at the top. The residue, which was ■termed hash, was then tipped out, the larger bones removed and the balance, a somewhat unsavoury and evilsinelling mess, was wrapped in packing, squeezed in a press, dried in a rotarj' drier, and then sent to a crusher. After this it was bagged and found . a market as a crude fertilizer.

That system was in vogue till nearly 1931. After that time, however, new machines were introduced. The boiler was there, but with new fittings. As large a piece as a quarter of beef can be fed in, and before it reaches the boiler proper it passes through cutters and grinders, which deal with bone as well as muscle. The cooking is done by means of steam round the outside of the boiler proper, and the meats cook by virtue of raising the temperature of the Julies in them. The moisture is taken out by exhaustion to. the atmosphere. The charge is tipped and enters a centrifugal basket whirled at one mile per minute, by which process the last vestige of fat is removed. Drying then follows,’ and the resultant is a valuable fertilizer or alternatively a .feeding meal.